Using the conventional meteorological observation data, T639 numerical prediction product FY-2E satellite cloud image and related quantitative products, the process of local thunderstorms in northern Shaanxi on July 29, 2014 was analyzed,based on the three elements of thunderstorm, the relationship between mesoscale instability and thunderstorms, the similarities and differences between lifting and triggering, and the relationship between weather system and thunderstorm mechanism were discussed,and analyzed the physical quantity of the thunder-storm mechanism and the mesoscale environment which was favorable to the occurrence of the thunderstorm.The results showed that the thun-derstorm was generated under the condition of unstable stratification, and the establishment of instability was conducive to the formation and development of thunderstorm mechanism.The thunderstorm area had a strong gradient of humidity, which was favorable for the vertical circula-tion of the thunderstorm.Rising support in the wet air area, sinking area in the dry area, the further development of the vertical circulation cir-cle in turn maintained the wet tongue, which was a strong convection trigger mechanism.Favorable mesoscale environmental field and boundary layer formation were thunderstorm triggering mechanisms.The high-level diffuse field and short-profile configuration helped the lower 850 hPa and ground convergence lines to trigger thunderstorms.%利用常规气象观测资料、T639数值预报产品FY-2E卫星云图及相关定量产品,分析了2014年7月29日陕北出现的一次局地雷暴天气过程,基于雷暴发生的三要素讨论了中尺度不稳定与雷暴发生之间的关系、抬升与触发的异同以及天气系统与雷暴抬升机制之间的关系,并对产生雷暴机制的物理量和有利于雷暴发生的中尺度环境进行分析.结果表明,雷暴是在条件不稳定层结下产生的,位势不稳定的建立有利于雷暴机制的形成与发展;雷暴发生区形成较强的湿度梯度,有利于雷暴发生区产生垂直环流.上升区在湿空气区,下沉区在干区,这个垂直环流圈的进一步发展反过来又维持了湿舌,是强对流的一种触发机制.有利的中尺度环境场和边界层辐合线的形成是雷暴的触发机制.高层的辐散场与短波槽的配置,有助于低层850 hPa和地面辐合线触发雷暴.
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